It is known that various surface characteristics are developed by coating inorganic material surfaces with various compounds or polymers. In particular, when a fluorine-based compound is used for surface treatment, surface modification can be applied for not only water-repellency, but also oil-repellency, due to characteristics of fluorine atoms. Thus, such fluorine-based compounds are used for coating on various substrates.
In particular, highly water- and oil-repellency coatings can be obtained by applying a surface-treating agent having a C8-perfluoroalkyl group to substrates. However, it is recently reported that compounds containing a perfluoroalkyl group having 7 or more carbon atoms induce intracellular communication inhibition, which is considered to be a carcinogenic factor, in in-vitro tests using cell strains; that this inhibition depends on the length of the fluorinated carbon chain, rather than the functional groups; and that the longer carbon chain the higher inhibitory actively. The production of monomers using fluorinated long-carbon-chain compounds has been restricted.
Moreover, fluorine-containing alcohols containing a perfluoroalkyl group having 6 or less carbon atoms problematically have lack of sufficient adhesion to inorganic substrates such as glass, metal, and stone.
Patent Document 1 discloses a ceramic slurry in which boron oxide B2O3 is used as a ceramic powder of the ceramic slurry, the hydroxyl group content of a resin binder, which is used polyvinyl butyral [PVB], is 50 mol % or less based on the amount of boron, and the moisture content of an organic solvent is 10 mol % or less based on the amount of boron.
Here, the use of boron oxide as the powder of the ceramic slurry is supposed to suppress the reaction represented by the following formula:B(OH)3+2H2O→B(OH)4−+H3O+
In addition, Patent Document 1 indicates that, due to the amount of hydroxyl groups in the slurry set to 50 mol % or less based on the substance amount of boron, gelation can be prevented, and when the ceramic slurry is applied to a PET film or the like, removal from the film can be suppressed. Ceramic slurries using boric acid are regarded as Comparative Examples.